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Cisco ATA 186 and Cisco ATA 188 Analog Telephone Adaptor Administrator’s Guide for MGCP (version 3.0)
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Chapter 6 Configuring and Debugging Fax Services
Using Fax Pass-through Mode
Note For detailed information on setting up your IOS gateways and on feature availability, refer to the
document Cisco Fax Services over IP.
Enable Fax Pass-through Mode
The supporting Cisco gateway can enable fax pass-through mode using system-level or dial-peer-level
commands.
System Level commands
Enable the fax pass-through feature using the following system-level commands:
Procedure
Step 1 Run the following command:
voice service voip
Step 2 Run the following command:
modem passthrough NSE [payload-type number] codec {g711µ/law | g711alaw} [redundancy]
[maximum-sessions value]
The definitions of the command parameters are as follows:
• The payload-type parameter default is 100. Valid values are from 98 to 119.
The NSE payload number must be the same on both the Cisco ATA and the Cisco gateway.
• The codec parameter must be G.711µ−law for faxes sent over a T1 trunk or G.711A-law for faxes
sent over an E1 trunk.
• The redundancy parameter enables RFC 2198 packet redundancy. It is disabled by default.
• The maximum sessions parameter defines the number of simultaneous fax pass-through calls with
redundancy. The default is 16. Valid values are 1 to 26.
Step 3 Turn off bits 14 and 15 of the Cisco ATA ConnectMode parameter. This enables the sending of fax
pass-through signals and the detection of incoming fax pass-through signals using the Cisco proprietary
method.
Note The NSE payload-type number, fax pass-through codec (G.711µ-law or G.711A-law) and redundancy
parameters must have the same settings for the Cisco ATA that they have for supporting Cisco gateways.